Glass coated member



Oct. 26, 1965 c, 5. BROWN 3,213,517

GLASS COATED MEMBER Original Filed Jan. 2, 1962 INVENTOR. CARL 6. BROWNg g BY A rus $Star-Ke,

United States Patent 3,213,517 GLASS COATED MEMBER Carl S. Brown,Cleveland, Ohio, assignor to A. O. Smith Corporation, Milwaukee, Wis., acorporation of New York Original application Jan. 2, 1962, Ser. No.163,641, new Patent No. 3,156,033, dated Nov. 10, 1964. Divided and thisapplication Mar. 4, 1964, Ser. No. 355,143

4 Claims. (Cl. 29-130) This is a division of application Serial No.163,641, filed Jan. 2, 1962, now Patent No. 3,156,033 granted Nov. 10,1964.

This invention relates to a glass coated tubular member and particularlyto an improved fused glass-coated tubular member.

Tubular members have been internally and externally glass coated byapplying a suitable glass frit to the surface to be coated and thensupporting the member in a firing furnace to increase the temperature orto fuse the glass frit to the member. However, in fusing of the glass tothe tubular member, generally a substantial amount of furnace distortionor warping results. In certain applications, the degree of warpage mustbe highly minimized in order to provide a satisfactory use of theglass-coated roll.

This invention is particularly directed to a glass coated thin walledmetal shell which is supported by a separable cylindrical core member.The core member is inserted inside the metal shell and causes it toassume a true cylindrical configuration. As employed herein, glass isgenerally synonomous with vitreous enamel and the like. The presentinvention is particularly directed a composite, glass coated insulatingroll for use in processing of cellophane film.

Cellophane film will not generally accept or retain printing unless thesurface is oxidized. conventionally, the cellophane surface is subjectedto high voltage discharge which oxidizes the surface slightly. Inpractice, the discharge takes place as the cellophane passes over aroller having an insulating outer coating and under the discharge bar ofa high voltage source. Commercially glass of a proper thickness towithstand 20,000 volts is the most practical insulating coating for theouter surface of the roller. All other coatings which have beensuggested have been found to separate from the roller.

As previously noted, glass coating of rollers in a furnace or the likeresults in a substantial distortion and generally is so severe as tomake the device unsuitable for such applications. The present inventionis directed to a composite, glass coated roller which includes a coremember and a flexible glass coated sleeve which minimizes the furnacewarpage to a level which permits the production of the conventional highdischarge roll for cellophane processing or the like.

Generally, the present invention employs a laminar roller having a thinouter shell to which the glass coating is applied and an innersupporting and distortion eliminatmg core,

In accordance with the present invention the relatively thin-walltubular shell is covered with a suitable glass frit or the like andsupported in a vertical position within a furnace on a special alloyrack. Generally, the rack member includes a plurality of axially spacedspacer rings of a slightly smaller diameter than the internal diameterof the shell such that the tube can be rotated on the alloy rack.

After a fused glass coating is built up on the shell to the desiredthickness, the assembly is removed from the furnace and a relativelyheavy wall tubular liner or core is forced into the thin-wall shell andforces the latter out to a substantially true round form. Generally, ithas ice been found desirable to provide a lubricating material on boththe internal surface of the tubular shell and the exterior surface ofthe core.

Appplicant has found that the glass follows the outward movement of thetubular shell without separation of glass from the shell if the yieldpoint of the steel is not exceeded. It appears that the assembly takesadvantage of the limited flexibility of the glass to adjust itself tothe pressure exerted by the inner core as it is forced through the outertubular wall.

The present invention thus provides a glass coated tubular member withsubstantial elimination of the warpage caused during the fusion of theglass coating to the surface of the tubular member.

The drawings furnished herewith illustrate the best mode presentlycontemplated for carrying out the invention.

In the drawings:

FIG. 1 is a fragmentary view of a finished tubular roll or member;

FIG. 2 is an elevational view of a tubular roll secured to a hangerwithin a furnace for fusing of a glass coating thereto;

FIG. 3 is an enlarged fragmentary view of FIG. 2;

FIG. 4 is an elevational view illustrating the forcing of an inner coreinto a glass coated tubular shell with parts broken away todiagrammatically illustrate the lubrication of the parts; and

FIG. 5 is a fragmentary view similar to FIG. 3 illustrating theinvention applied to the glass coating of a somewhat larger diametertubular shell.

Referring to the drawings and particularly to FIG. 1, a glass coatedtubular roller constructed in accordance with the present invention isillustrated and includes an inner tubular core 1 of a relativelysubstantial thickness and an outer thin-wall tubular shell 2 telescopedwith the inner core 1. Whereas the inner core 1 is generally a heavyself-supporting member, the thin-wall shell 2 is a substantiallynon-self-supporting member. As applied to an insulating discharge rollerfor cellophane processing, the wall thickness of the outer shell may beabout .0005 inch and the core about one inch.

A glass coating 3 is fused to the outer exterior surface of thethin-wall shell 2 to provide an insulating surface over which thecellophane film, not shown, is passed.

Referring to FIGS. 2 and 3, the tubular shell 2 is mounted for glasscoating as follows.

A cylindrical rack 4 of a somewhat greater length than the shell 2includes a top hanger 5 by which the rack is secured to a suitable hookor rod support 6 and supported within a suitable furnace or the like,not shown. The thin-wall shell 2 is carried by the rack 4 in a positionfor fusing of a glass frit or the like thereto.

The rack 4 includes a series of alternate supporting shafts 7 andlocating or spacer rings 8 which are interconnected in axial end-to-endrelation as by butt welding or the like. Shafts 7 and rings 8 are solidand formed of a stainless steel alloy or the like which are notdistorted by the temperature employed in firing the coating 3. Thediameter of the spacer rings 8 is slightly greater than that of theshafts 7 and slightly less than the internal diameter of the thin-wallshell 2, as most clearly shown in FIG. 3. This clearance provides easeof assembly and disassembly of the shell 2 with respect to rack 7 evenat elevated temperatures.

A supporting disc 9 is bolted as by a bolt 10 or otherwise secured tothe lowermost spacer ring 8. The outer edge of the disc 9 is tapered asat 11 and extends or diverges radially outwardly of the adjacent ring 8to present the tapered edge to the lower end of the thin-Wall shell 2.The inner edge 12 of the thin-wall shell 2 rests on the tapered edge 11and supports the shell 2 on the inner edge thereof during the fusing ofthe glass coating. Any glass which flows downwardly will not becollected on the disc as may occur with a straight ledge. Thiseliminates a possible cause of spalling or breaking away of the glass atthe edge of shell 2.

After a sufficient thickness of glass has been fused to shell 2 to formthe desired coating 3, the glass-coated tubular shell 2 is removed fromthe furnace and placed in an assembly machine 13 as shown in FIG. 4.

The illustrated machine 13 is generally a lathe type unit adapted tosupport the glass-coated shell 2 for axial alignment with the innercore 1. A stop 14 is secured abutting the one end of shell 2 with theopposite end adjacent core 1. A ram 15 is secured to core 1 and is movedaxially to force core 1 into shell 2.

The core 1 is machined to an outer diameter slightly smaller than theinside diameter of shell 2 and preferably to provide a .0020 to .0025inch clearance. The end of the core 1 immediately adjacent the end ofthe shell 2 is also provided with a slight taper 16 to center core 1with shell 2 during the initial movement of the core into the shell 2.

Assembly is also desirably facilitated by applying to the matingsurfaces of the core 1 and the shell 2 a suitable lubrication 17 and 18of white lead in oil or any other suitable medium.

The core 1 is pressed into the shell 2 and forces the shell 2 to anessentially true cylindrical round exterior configuration.

The core 1 may be forced into the shell 2 with the shell either hot orcold.

Applicant has constructed 3 /2 inch diameter rollers in lengths up to 78inches with the finished roller run-out well within the .060 inchtolerance which has been required as a minimum for cellophane processingapplications and the like. Generally, the apparatus constructed had aninternal diameter of 2.875 and a finished outer diameter tolerance lyingbetween 3.580 and 3.620 inches. The glass-fired shells 2 employed had arun-out of as much as 0.120 inch. This was reduced after assembly withthe machined inner core 1 to 0.040 inch and thus completely satisfactoryfor the highest commercial standard presently employed in the cellophaneprocessing industry.

The present invention employs the restricted flexibility of the glasscoating 3 to allow limited movement of the shell 2 and elimination ofdistortion.

Referring particularly to FIG. 5, a view similar to FIG. 2, the rack 4is illustrated with an increased diameter shell 2 mounted in place forfiring a glass coating thereto. Generally, corresponding elements inFIG. and FIGS. 2 and 3 are similarly numbered for simplicity and clarityof explanation. Additional spacer rings 19 are concentrically secured tothe spacer rings 85 by recessed and circumferentially spaced set screws20 or the like. The edges of rings 19 are tapered to provide a smalllocating surface 21 adjacent the shell 2. Rings 19 are also formed toprovide clearance between surfaces 21 and the shell 2. An enlargedsupporting disc 22 is secured to the bottom spacer ring 8 and includes atapered edge 23 aligned with the lower end of the shell 2. Thesupplemental spacer rings 19 increase the flexibility for the firingfixtures while maintaining expense at a minimum.

To provide for shells 2 of varying length, the lowermost shafts 7 andrings 8 can be made as a subassembly and secured in place with asuitable stud 24 having threads corresponding to the bolt 10 as shown inFIG. 5.

The present invention thus provides a glass coated roller having aminimum of run out.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. A glass coated tubular member for electrostatic processingcomprising,

(a) a tubular supporting core which is completely self supporting andhas a true cylindrical outer surface, said core having a wall thicknessof approximately one inch,

(b) a thin metal tubular shell telescoped over the core and having awall thickness of approximately .0005 inch and permitting flexiblemovement of the shell, and

(c) a glass coating fused to the exterior surface of the thin-wallshell.

2. The glass coated tubular member of claim 1 wherein said roller isdesigned to have an outer diameter of essentially 3 /2 inches within atolerance of .060 inch.

3. A glass coated tubular member for electrostatic processingcomprising,

a supporting core which is completely self supporting and has a truecylindrical outer surface,

a thin metal tubular shell telescoped over the core and having a wallthickness of approximately .0005 inch and permitting flexible movementof the shell, and

a glass coating fused to the exterior surface of the thin-wall shell.

4. A glass coated tubular metal member for use in electrostaticprocessing comprising,

a self-supporting core having a generally true cylindrical outersurface,

and a thin walled metal shell having a glass coating fused thereonadapted to be telescoped over said core, said metal shell and said glasscoating having a flexibility permitting movement of the shell to a truecylindrical round exterior from a slightly non-cylindrical configurationwithout exceeding the yield point of the metal or the glass coating whenin final telescoped position on said core, whereby said glass coatedmetal shell conforms to the true cylindrical shape of said core whenmounted thereon without any spalling of the glass.

References Cited by the Examiner UNITED STATES PATENTS 1,394,684 10/21Matsuo. 1,619,371 3/27 Rogers et al.

WALTER A. SCHEEL, Primary Examiner.

LOUIS O. MAASSEL, Examiner.

4. A GLASS COATED TUBULAR METAL MEMBER FOR USE IN ELECTROSTATICPROCESSING COMPRISING, A SELF-SUPPORTING CORE HAVING A GENERALLY TRUECYLINDRICAL OUTER SURFACE, AND A THIN WALLED METAL SHELL HAVING A GLASSCOATING FUSED THEREON ADAPTED TO BE TELESCOPED OVER SAID CORE, SAIDMETAL SHELL AND SAID GLASS COATING HAVING A FLEXIBILITY PERMITTINGMOVEMENT OF THE SHELL TO A TRUE CYLINDRICAL ROUND EXTERIOR FROM ASLIGHTLY NON-CYLINDRICAL CONFIGURATION WITHOUT EXCEEDING THE YIELD POINTOF THE METAL OR THE GLASS COATING WHEN IN FINAL TELESCOPED POSITION ONSAID CORE, WHEREBY SAID GLASS